在项目中有时会遇到大文件上传，经常会出现链接超时的问题，所以就需要使用文件分片上传的方式来上传大文件。实现原理就是，在前端将文件分成指定大小的“文件块”，分成多次上传，每次上传前先向后台查询已经上传成功的文件的大小，然后从指定的位置切割一块文件，进行上传，后台接收到文件块后追加到指定的文件中。
这篇博客适合有一些后台基础的朋友，或者有后台配合的前端。
这里需要后台提供两个接口，一个上传文件的接口，一个查询已上传文件大小的接口。
前端代码：https://github.com/li5454yong/FileUpload.git
这里放上后台主要代码
package com.fs.controller;import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FileWriter; import java.io.IOException; import java.io.InputStream; import java.io.RandomAccessFile; import java.util.Iterator; import java.util.Map; import javax.annotation.Resource; import javax.servlet.http.HttpServletRequest; import org.apache.commons.lang3.StringUtils; import org.csource.ClientGlobal; import org.csource.common.MyException; import org.csource.fastdfs.FileInfo; import org.csource.fastdfs.StorageClient; import org.csource.fastdfs.TrackerClient; import org.csource.fastdfs.TrackerServer; import org.junit.Test; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.multipart.MultipartFile; import org.springframework.web.multipart.MultipartHttpServletRequest; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisShardInfo; import com.alibaba.fastjson.JSON; import com.fs.entity.UploadedFileInfo; import com.fs.util.UploadUtil; /** * @author admin * * 2016年12月20日下午8:59:38 */ @Controller public class FastDFSUpLoadController { @Resource private UploadUtil uploadUtil; @RequestMapping(value = "v1/uploadSize", method = RequestMethod.POST) @ResponseBody public Long uploadSize(HttpServletRequest request) { String name = request.getParameter("name"); Long size = Long.parseLong(request.getParameter("size")); try { JedisShardInfo jedisShardInfo = new JedisShardInfo("192.168.0.12"); Jedis jedis = new Jedis(jedisShardInfo); String str = jedis.get(name); UploadedFileInfo uploadedFileInfo = null; // 如果首次上传，已上传大小为 0 if (StringUtils.isEmpty(str)) { uploadedFileInfo = new UploadedFileInfo(); jedis.set(name, JSON.toJSONString(uploadedFileInfo)); jedis.close(); return 0L; } uploadedFileInfo = JSON.parseObject(str, UploadedFileInfo.class); jedis.close(); //已经全部上传 if(size <= uploadedFileInfo.getSize()){ System.out.println("上传完成"); } //UploadUtil.getFileInfo(uploadedFileInfo.getFileId()); return uploadedFileInfo.getSize(); } catch (Exception e) { e.printStackTrace(); return 0L; } } @RequestMapping(value = "v1/uploadFile", method = RequestMethod.POST) @ResponseBody public int upload(HttpServletRequest request) { // CommonsMultipartResolver resolver = new // CommonsMultipartResolver(request.getSession().getServletContext()); MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request; Iterator<String> t = multiRequest.getFileNames(); MultipartFile fileDetail = multiRequest.getFile(t.next()); String name = request.getParameter("name"); JedisShardInfo jedisShardInfo = new JedisShardInfo("192.168.0.12"); Jedis jedis = new Jedis(jedisShardInfo); UploadedFileInfo uploadedFileInfo = JSON.parseObject(jedis.get(name), UploadedFileInfo.class); uploadedFileInfo.setFileName(name); String path = "d:/testUpload"; File file = new File(path); if (!file.exists() && !file.isDirectory()) { boolean b = file.mkdirs(); } RandomAccessFile randomFile = null; try { randomFile = new RandomAccessFile(path+"https://www.jb51.net/"+name, "rw"); randomFile.seek(randomFile.length()); randomFile.write(fileDetail.getBytes()); uploadedFileInfo.setLocalPath(path+"https://www.jb51.net/"+name); uploadedFileInfo.setSize(randomFile.length()); } catch (IOException e) { e.printStackTrace(); }finally{ try { randomFile.close(); } catch (IOException e) { e.printStackTrace(); } } // 将上传文件信息保存到redis jedis.set(name, JSON.toJSONString(uploadedFileInfo)); jedis.close(); return 0; } }
以上所述是小编给大家介绍的JS异步文件分片断点上传的实现思路，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！
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